Electrical disconnecting device



Dec. 15, 1936. M. G. DAHL 2,064,736

' ELECTRICAL DISGONNECTING DEVICE Filed June 18, 1936 l 1s 22 22 lo i lmnmm mum; C

.lll' mmm INVENTOR MAGNUS G. DAHL BY HIS ATTORNEYS m MM Patented Dec. 15}, 1936 ELECTRICAL DISCONNECTING DEVICE Magnus G. Dahl, West Hartford, Conn, assignor to The Arrow-Hart & Hegeman Electric Company, Hartford, Conn, a corporation of Connecticut Application June 18, 1936, Serial No. 85,984

16 Claims.

This invention relates to devices for the semipermanent or infrequent connection or disconnection of branches of circuits from other branches. Devices of this type are commonly called disconnect blocks. The connections and disconnections made in these blocks are usually made when no current is flowing through the device.

It is an object of this invention to provide a disconnect block in which the disconnection of the terminals may be accomplished in a more effective manner than heretofore.

Another object of the invention is to provide a disconnecting block in which the connecting element is positively moved and held in open-circuit position by means additional to the customary manual tool or screw driver.

Another object of my invention is to provide a disconnecting device of the type above specified in which the connecting bolt is positively moved to open-circuit position and held therein by means, such as a spring, when the bolt has been unscrewed approximately one full turn.

Other objects and advantages of my invention will become apparent as it is described in connection with the accompanying drawing. I

In the drawing Figure 1 is a plan View of a disconnecting block embodying the principles of my invention;

Figure 2 is a longitudinal section view of the invention with the section being taken along line 22 of Figure 1;

Figure 3 is an exploded view of the conducting parts and other parts associated therewith in the invention illustrated in Figures 1 and 2.

Referring to the drawing the conducting parts are mounted upon a substantially rectangular symmetrical block II] of any suitable insulating material, such as porcelain. Running centrally along the block and extending up from the upper surface is a rib or barrier l2. Inasmuch as the device is symmetrical and identical on each side of the barrier I2 the description of the parts on one side will suflice. In Figure 1 the conducting parts have been removed from one side of the block in order to show more clearly the formation of the block beneath the conducting parts. On each side of this rib or barrier I 2 there are aligned conducting members or terminal plates, such as I4 and I6, stamped from sheet metal in the form of strips as best shown in Figure 3. Recesses or channels l8, for the terminal plates, are provided or formed in the upper face of the block in parallel relation on opposite sides of the rib or barrier I2.

" The width of these channels is slightly greater than the width of the terminal plates I4 and I6 whereby the terminal plates I4 and I6 may be seated in the channels. The terminal plates I4 and I6 are secured in the channels I8 at opposite ends by means of bolts I5 and I1 passing through the block from the bottom and taking into threaded openings M and Ill in the plates. Adjacent ends of the terminal plates l4 and I6 are provided with arcuate recesses I I and l6 which fit around a reduced neck 20 on a washer designated generally by the numeral 20. The main body 20 of the washer underlies the ends of the terminal plates I4 and I6 when the parts are in assembled position, as illustrated in Figures 1 and 2.

The insulating washer 20 overlies a circular well 22 upon the bottom of which rests a helical compression spring 26 which presses upwardly against a metal annulus 26 of smaller diameter than the well 22 so as to be able to move axially in the well. Into the central opening 26 of the annulus extends an axial nub 28 on the lower end of a bolt designated generally by the numeral 28. This bolt has an unthreaded shank portion 28 and upper and lower threaded shank portions 28 and 28 above and below the unthreaded portion. The threaded portion 28 has about one turn of a double thread thereon while the upper threaded portion 28* has several turns of a double thread of the same pitch and diameter as the lower thread. The whole shank of the bolt is of such diameter as to pass freely thru the insulating washer 20. The bolt 28 may have an hexagonal head 28 with a slot therein for a screwdriver. Beneath'this head there is a circular flange or collar 28 which may be formed integrally with the bolt or may be secured thereon in any suitable fashion so as to move as a unit with the bolt. This collar forms the means to bridge the gap between the terminal plates I4 and I6, when the bolt is screwed down.

The screw threads of the bolt 28 are adapted to take into a hexagonal nut 30 which lies beneath the insulating washer 20 and is seated in a hexagonal enlargement 22 near the top of the well 22. A larger enlargement 22 of circular form is provided above the hexagonal enlargement 22 and this circular enlargement provides a seat for the insulating washer 20. Thus when the terminal plates M and I6 are screwed in place. they hold the washer 20 and nut 30 in their seats, fixedly. Also the spring 24 and annulus 26 are held in the well beneath the nut 30.

It may now be seen that when the parts are assembled as shown in Figure 2 and the bolt 28 is screwed down until the engagement of the threads 28 with the nut causes the flange or collar 28 to engage the upper surfaces of the terminal plate members I4 and I6, current will be passed through the device from the plate l4 through the flange 28 to the plate 16. Preferably the parts are proportioned and formed so that when the bolt 28 is screwed down tight upon the terminal plates [4 and I6 upper threaded portion 28 will have turned approximately one full turn into the nut 30. Thus when the bolt 28 is unscrewed one full turn the upper threaded portion 2% will free itself from the nut 30 and the pressure of the spring 24, being transmitted through the annulus 26 to the bolt 28, will cause the bolt to jump upwardly away from the terminal plates [4 and 18. This upward movement will be stopped when the lower threaded portion 28 engages with the nut 3|]. This is the normal open-circuit or disconnecting position. If it is desired to remove the bolt 28, further unscrewing motion may be given it until the lower threaded portion 28 frees itself from the nut 30.

From the foregoing it will be apparent that I have provided a simple and effective means for positively holding the bridging bolt 28 out of contact with the terminal plates l4 and I 6 and I have also provided a positive means for moving the bolt into that position after it has been unscrewed to a predetermined degree, preferably one full turn. Obviously, however, instead of being released upon one full turn the parts may be proportioned to cause release of the bolt after it has been unscrewed a fraction of a turn or more than one turn, as desired.

Many changes within the scope of my invention will occur to those skilled in the art and therefore I do not limit myself to the specific form of the invention as illustrated.

I claim 1. A disbonnect block comprising an insulating base, a pair of aligned terminal plates secured upon said base, an insulator between adjacent ends of said terminal plates and having portions underlying said ends, said base having a well beneath said insulator, a nut fixedly mounted in said well, a compression spring seated in said well, a member pressed outwardly of said well by said spring, and a bolt having spaced threaded portions engageable with said nut and an unthreaded portion slidable thru said nut, said bolt being urged outwardly of said well by said spring and movable freely thru said nut when the innermost threaded portion of the bolt becomes disengaged from the thread of the nut, and means on said bolt to engage said plates when said bolt is screwed as fully as possible onto said nut.

2. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, an insulator between said terminal plates and having portions underlying said terminal plates, said base having a well beneath said insulator, a nut fixedly mounted in said well, a compression spring seated in said well, a member pressed outwardly of said well by said spring, and a bolt having spaced threaded portions engageable with said nut and an unthreaded portion slidable thru said nut, said bolt being urged outwardly of said well by said spring and movable freely thru said nut when the innermost threaded portion of the bolt becomes disengaged from the thread of the nut, and means on said bolt to engage said plates when said bolt is screwed as fully as possible onto said nut.

3. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, an insulator fixedly positioned between said plates, said base having a well beneath said insulator, a nut fixedly mounted in said. well, a compression spring seated in said well, a member pressed outwardly of said well by said spring, and a bolt having spaced threaded portions engageable with said nut and an unthreaded portion slidable thru said nut, said bolt being urged outwardly of said well by said spring and movable freely thru said nut when the innermost threaded portion of the bolt becomes disengaged from the thread of the nut, and means on said bolt to engage said plates when said bolt is screwed as fully as possible onto said nut.

4. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, said base having a well between said plates, a nut fixedly mounted in said well, a compression spring seated in said well, a member pressed outwardly of said well by said spring, and a bolt having spaced threaded portions engageable with said nut and an unthreaded por tion slidable thru said nut, said bolt being urged outwardly of said well by said spring and movable freely thru said nut when the innermost threaded portion of the bolt becomes disengaged from the thread of the nut, and means on said bolt to engage said plates when said bolt is screwed as fully as possible onto said nut.

5. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, a nut fixedly located in a plane parallel to but spaced from said plates, a bolt hav ing spaced threaded portions engageable with said nut and an unthreaded portion slidable thru said nut, means on said bolt to engage said plates when said bolt is screwed as fully as possible into said nut, a spring pressing said bolt in direction to cause said means to disengage said plates and causing said bolt to move freely within said nut when one of said threaded portions becomes disengaged from the thread of said nut.

6. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, a nut fixedly located in a plane parallel to but spaced from said plates, a bolt having a threaded portion engageable with said nut and an unthreaded portion freely slidable thru said nut, means on said bolt to engage said plates when said bolt is screwed as fully as possible into said nut, a spring pressing said bolt in direction to cause said means to disengage said plates and causing said bolt to move freely within said nut when said threaded portion becomes disengaged from the thread of said nut.

7. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, a nut fixedly located in a plane parallel to but spaced from said plates, a bolt having a threaded portion engageable with said nut and an unthreaded portion freely slidable thru said nut, means on said bolt to engage said plates in one position of said bolt, a spring pressing said bolt in direction to cause said means to disengage said plates in another position of said bolt.

8. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, a fixedly located nut insulated from said plates, a bolt engageable with said nut and having means for engagement with said plates in one position of the bolt, and a spring pressing said means out of engagement with said plates in another position of said bolt.

9. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, a fixedly located nut insulated from said plates, a bolt having spaced threaded portions and an unthreaded portion, means on said bolt to engage said plates when one of said threaded portions is screwed as fully as possible into said nut, and a spring moving said bolt out of said engaging position with the free movement of said unthreaded portion thru said nut when said one threaded portion is disengaged from said nut.

10. A disconnect block comprising an insulating base, a pair of terminal plates secured thereon, a nut held in position by said plates, means insulating said nut from said plates, a bolt having a threaded portion engageable with said nut and means on said bolt engaging with said plates when said bolt is screwed into said nut fully.

11. A disconnect block comprising an insulating base, a pair of terminal plates secured thereon, a nut held in position by said plates, means insulating said nut from said plates, a bolt having a threaded portion engageable with said nut, means on said bolt engaging with said plates when said bolt is screwed into said nut fully and spring means moving said bolt into disconnecting position when said bolt is disengaged from said nut.

12. A disconnect block comprising an insulating base, a pair of terminal plates secured thereon, a nut held in position by said plates, means insulating said nut from said plates, a bolt having a threaded portion engageable with said nut and an unthreaded portion slidable freely within said nut, and means on said bolt engaging with said plates when said bolt is screwed into said nut fully, and spring means moving the unthreaded portion of said bolt thru said nut into disconnecting position when said threaded portion is disengaged from said nut.

13. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, a nut fixedly located in a plane parallel to but spaced from said plates, a bolt having a threaded portion engageable with said nut and. an unthreaded portion freely slidable thru said nut, means on said bolt to engage said plates in one position of said bolt, a spring pressing said bolt in direction to cause said means to disengage said plates in another position of said bolt, the threaded portion of said bolt having a double thread of such pitch that it disengages itself from said nut in substantially one complete turn.

14. A disconnect block comprising an insulating base, a pair of terminal plates secured upon said base, a fixedly located nut insulated from said plates, a bolt engageable with said nut and having means for engagement with said plates in one position of the bolt, and a spring pressing said means out of engagement with said plates in another position of said bolt, the threaded portion of said bolt having a double thread of such pitch that it disengages itself from said nut in substantially one complete turn.

15. A disconnect block comprising an insulating base, a pair of terminal plates secured thereon, a nut held in position by said plates, means insulating said nut from said plates, a bolt having a threaded portion engageable with said nut and means on said bolt engaging with said plates when said bolt is screwed into said nut fully, the threaded portion of said bolt having a double thread of such pitch that it disengages itself from said nut in substantially one complete turn.

16. A disconnect block comprising an insulating base, a pair of terminal plates secured thereon, a nut held in position by said plates, means insulating said nut from said plates, a bolt having a threaded portion engageable with said nut and an unthreaded portion slidable freely within said nut, and means on said bolt engaging with said plates when said bolt is screwed into said nut fully, and spring means moving the unthreaded portion of said bolt thru said nut into disconnecting position when said threaded portion is disengaged from said nut, the threaded portion of said bolt having a double thread of such pitch that it disengages itselfv from said nut in substantially one complete turn.

MAGNUS G. DAHL. 

